Hi,
I am designing an audio playback system where only one two sources will be active at any time, either mp3 playback through the VS1053 or the output from a bluetooth audio receiver. I am currently looking for the simplest setup for mixing these signals that will not deteriorate audio quality too much and I have a couple of questions:
- Could I use the line1 input on the VS1053b and control which source is active by routing signals inside the VS1053 through a MCU? I am already feeding the mp3 stream through an SPI connection. This would be simplest solution because it would not require any changes to my hardware setup.
- Alternatively, what kind of switching circuitry would you put between the two analog outputs and the (class D) amp input? Would an analog switch such as https://www.maximintegrated.com/en/MAX4992 do the job?

Alternatively, you can initialize the encoding mode with a suitable samplerate to route the signal from analog input(s) to the analog outputs. (You don't need to read out the encoded data, so you don't even need the small patch, simply write AICTRL0 and start encoding by setting SM_ENCODE and SM_SOFT_RESET and other applicable bits in SCI_MODE.)

Hi,
I finally have time to try out your suggestions. Just a quick question: Which bit do you mean by SM_ENCODE? I cannot find any mention of it in the reference manual. Did you mean SM_ADPCM by any chance?